1. Field of the Invention
The present invention relates to a chain alignment structure of a transmission for a bicycle.
2. Description of Related Art
A transmission for a bicycle according to the present invention relates to a chain alignment structure of a bicycle transmission which includes a drive sprocket wheel which is rotatably driven by a crankshaft, a driven sprocket wheel which is drivably connected with an output shaft which is rotated in an interlocking manner with a drive wheel (usually a rear wheel) of a bicycle, and an endless chain which is wound around the drive sprocket wheel and the driven sprocket wheel. In the related art, the chain alignment structure of a transmission having such a construction is not known. In view of this, related art from a similar technical field will be discussed.
Conventionally, the deflection of a chain attributed to the transmission or the vibration which is generated between a reel-in side of the drive sprocket wheel and a reel-out side of the driven sprocket wheel is received such that the chain 8 is received from below by a chain receiving portion 12 which is formed on an upper portion of a pulley arm 9 which is fixed to a chain stay 2′ (numerals being numerals described in following cited document). However, since the chain receiving portion is arranged only below the chain, although the downward deflection of the chain is restricted, the chain receiving portion does not serve to restrict the upward movement of the chain (for example, see JP-UM-55-1551).